The Delta as A Source of Drinking Water Monitoring Results - 1983 to 1987 INTERAGENCY DELTA HEALTH ASPECTS MONITORING PROGRAM Department of Water Resources Central District August 1989 Gordon K Van Vleck George Deukmejian David N. Kennedy Secretary for Resources Governor Director The Resources Agency State ofCalifornia Department ofWater Resources Copies of this report at $10.00 each may be ordered from: State of California Department of Water Resources P. O. Box 942836 Sacramento,Cll 94236-0001 Make checks payable to Department ofWater Resources. California residents add sales tax. FOREWORD -,~_.........., --------------------------- Sound water resources management requires comprehensive data collection to enable tltlderstanding offactors that can affect water quality. The Department of Water Resources, in cooperation with other water agencies, initiated the Interagency Delta Health Aspects Monitoring Program in 1983 in response to recommendations by a scientific panel appointed by the Director to assess human health aspects of Delta water supplies. Because of their potential effects on human health, the program focuses on the following constituents: sodium, selenium, asbestos, trihalomethane precursors, pesticides, and other synthetic organic chemicals. The program has evolved into a combination of monitoring and special investiga­ tions related to the quality of Delta water supplies. Study priorities are determined and carried out by the Department through the guidance of a Technical Advisory Group, represented by participating water agencies. The Department of Health Services is also represented in the Technical Advisory Group, providing input on human health issues and laboratory quality assurance. This report presents an analysis of data collected in and near the Delta during the first five years of the program, January 1983 through December 1987. The report also provides an overview ofmajor factors that affect Bay-Delta water quality and identifies water quality considerations for the future. The Delta is an acceptable source of drinking water, which when treated meets· drinking water standards. The ability to meet drinking water standards at treat­ ment facilities depends, in part, on quality of the water being treated and regulatory requirements ofthe drinking water standards. Compliance with drink­ ing water standards may become more difficult in the future as a result ofproposed tightening of the standards. This program is an integral part of the Department's mission of water resource planning and protection of California's drinking water supplies. This monitoring program will continue to be responsive to health-related water quality concerns identified by the Technical Advisory Group. iii CONTENTS FOREWORD • 111 ORGANIZATION YI11 ACKNOWLEDGMENTS . IX SUMMARY 1 Results ofWater Quality Analyses 1 Total Trihalomethane Formation Potential 1 Sodium 2 Pesticides 2 Asbestos 2 Selenium . 2 Salinity, Electrical Conductivity, Ion Concentrations and Ion Ratios 2 Future Water Quality Considerations 4 RECOMMENDATIONS 5 Chapter 1. INTRODUCTION 7 Study Area 7 Field Work 7 Laboratory Work 8 Chapter 2. MAJOR FACTORS AFFECTING WATER QUALITY .13 Drinking Water Standards .13 Regulatory Controls in the Delta .13 Hydrologic Conditions .13 River Inflows . .13 Runoff and Outflow .14 Floods .15 Tides . .16 Water Exportation and Diversions .16 Agricultural Activities .16 Salt Management . .16 Pesticide Applications .17 Domestic And Industrial Activities .17 Chapter 3. 5-YEAR DATA ANALYSIS .21 Total Trihalomethane Formation Potential .21 Brominated THM Formation Potential .21 v Selenium .22 S()ditifil \ .22 Pesticides ... .23 Asbestos .24 Salinity, Electrical Conductivity, and Ion Ratios .~4 Relationships Between Flows and Delta Water Quality .25 WaterYe~ 1983 .25 Water Year 1984 .25 Water Year 1985 .25 WaterYe~ 1986 .26 WaterYe~ 1987 .26 Correlations Between Total THM Formation Potential and Other Factors .26 Chapter 4. FUTURE WATERQUALITY CONSIDERATIONS .39 Natural Disasters .39 Delta Flood Protection Act · 39 Proposed Construction Projects · 39 Delta Wetlands Project . · 39 Clifton Court Forebay Intake · 39 REFERENCES, ". .41 Appendixes AppendixA. $UMMARY OF MONITORING, JULY 1986 THROUGH DECEMBER 1987 .43 Appendix B. CLIFTON COURT FOREBAY WATER QUALITY ANALYSIS .45 Appendix C. PREVIOUS STUpIES .57 Appendix D. PESTICIDE SELECTION SCHEME .,. 63 Appendix E. SAMPLING, ANALYSIS, AND QUALITY ASSURANCE/ CONTROL PROCEDURES . 67 AppendixF. DRINKING WATERSTANDARDS AND ADVISORIES .91 Appendix G. MONITORING PROGRAM DATA .95 Appendix H. DAYFLOW MODEL DESCRIPTIO,N 147 vi Figures Figure 1 Trihalomethane Formation Potential in the Delta, 5-Year Median, 1983-1987 3 Figure 2 Statutory Delta 9 Figure 3 Station Locations .11 Figure 4 Comparison ofSacramento River Flow Estimates .17 Figure 5 Monthly Average Flows .18 Figure 6 Irrigation Diversion Points .19 Figure 7 Total THM Formation Potential in the Delta, 1983-1987 Lowest, Median, Highest .28 Figure 8 Total Bromomethane Formation Potential, 5-Year High, Low, Median .29 Figure 9 Total Bromomethane Formation Potential in the Delta Under High Flow Conditions, March 1986 .30 Figure 10 Total Bromomethane Formation Potential in the Delta Under Low Flow Conditions, October 1985 .31 Figure 11 Electrical Conductivity, 5-Year High, Low, Median .36 Figure 12 Molar Sodium to Chloride Ion Ratios, 1984-1987 .37 Tables Table 1 Delta Statistics .10 Table 2 Frequency of Total Trihalomethane Formation Potential Values .27 Table 3 Frequency ofSelenium Concentrations, 1984-1987 .32 Table 4 Frequency ofSodium Concentrations, 1983-1987 .33 Table 5 Pesticide Monitoring Results, 1983-1987 .34 Table 6 Results ofAsbestos Sampling, 1984-1986 .35 Table 7 Simple Linear Regression Values .38 vii ORGANIZATION State of California GEORGEDE~,GOVERNOR The Resources Agency . .. GORDON K VAN VLECK, Secretary for Resources Department ofWater Resources DAVID N.KENNEDY, Director Robert G. Potter John P. Caffrey Larry A. Mullnix Deputy Director Chief Deputy Director Deputy Director Salle S. Jantz Susan N. Weber Assistant Director ChiefCounseL' DIVISION OF LOCAL ASSISTANCE James U. McDaniel . Chief .CENTRAL DISTRICT Jerry'D. Vayder . District Chief Randall L. Brown . Chief,Environmelltal Studies Branch This report was prepared under the supervision of Richard Woodard . Enyironmental Program Manager I By Judith Heath ~ Environmental SpeCialist IV Bruce Agee . Environmental Specialist IV And Marvin Jimg, Water Quality Consultant MARVIN JuNG & ASSOCIATES, INC. (DWR Contract B-56213) Sacramento, California .h With assistance from B. d. Archer . Wa.te:rQuality Engineer, Michael Sutliff " Sanitary EJ:lgineer William McCune Water Resources Engineering Associate Robert Atherstone Water Resources Engineering A~sociat~ Walt Lanibert Water Resdu:rces TechiiiCHmII Lori Weisser Water Resources Technician II Barbara Heinsch ·Student Assistant Hallie Whitfield ·Student Assistant Keith Healy ·Student Assistant David Kemena ·Student Assistant Eric Nichol ·Student Assistant Editing and reportproductionprovided by Vera L. Tharp · Research Writer viii ACKNOWLEDGMENTS The Department ofWater Resources is the lead agency conducting the Interagency Delta Health Aspects Monitoring Program. Program funding and technical assistance are provided by: East Bay Municipal Water District Contra Costa Water District Urban Water Contractors ofthe State Water Project including Metropolitan Water District ofSouthern California Santa Clara Valley Water District Alameda County Water District Alameda County Flood Control and Water Conservation District, Zone 7 The Department of Health Services participates in the program through its member­ ship in the Technical Advisory Group, which includes representatives of the other participating agencies. TECHNICAL ADVISORY COMMITTEE Keith Carns Dan Peterson, Environmental Specialist IV Director of Water Quality Division of Operations and Maintenance East Bay Municipal Utility District California Department of Water Resources John Coburn Andrew Florendo, Water Systems Technician Staff Engineer Alameda County Flood Control and State Water Contractors Water Conservation District, Zone 7 Isabel Gloege, Associate Civil Engineer David Spath, Ph.D., Sr. Sanitary Engineer Water Quality Division Public Water Supply Branch Santa Clara Valley Water District California Department of Health Services Michael Lanier, Supervisor Alexis Milea, Associate Sanitary Engineer Water Quality Public Water Supply Branch Alameda County Water District California Department of Health Services Edward Means, Assistant Director Michael G. Volz, Ph.D. Water Quality Environmental Biochemist Metropolitan Water District Sanitation and Radiation Laboratory of Southern California California Department of Health Services Greg Gartrell Division Engineer Contra Costa Water District ix SUMMARY The purpose of the Interagency Delta Health Aspects Monitoring Program, which began in 1983, is to obtain water quality information that will help in making decisions about the quality ofwater resources and to assess potential water treatment methods. This program is the only one ofits kind to provide comprehensive monitoring ofhuman health-related water quality conditions throughout the Sacramento-San Joaquin Delta. Major factors affecting Delta water quality are: seawater or estuarinewater. Bromides are also found in fresh water flowing into the Delta, particularly the » Regulatory controls, San Joaquin River. Bromides from seawater or es­ » Inflow, tides, precipitation, diversions, and